The invention described herein may be manufactured, licensed, and used by or for the U.S. Government.
1. Field of the Invention
The present invention relates to a composition suitable for simulating and evaluating chemical agent contamination. More particularly, the invention provides compositions which can be used to safely train military personnel in handling chemical agent decontamination.
2. Description of the Prior Art
The handling of chemical agent contamination is an important part of military training. The exposure of military personnel even to small amounts of real contaminants, i.e. nerve and/or blistering agents is impractical due to the risk of injury involved. There is therefore a need to use a relatively harmless composition which simulates the effects of such chemical agent contaminants without injuring trainees. The invention therefore provides a chemical agent simulant composition for operational evaluation of chemical agent contamination. It is useful for providing a measure of the extent of contamination from spills or dispersion devices, and the effectiveness of decontamination procedures. The inventive composition employs a unique combination of compatible detection materials which are environmentally safe and incorporate simulated vapor signature components, as well as a liquid fluorescence signature component. It provides a simulant chemical agent vapor signature for chemical detection systems, as well as a visible indicator of liquid contamination when irradiated with an ultraviolet light source. This system can be useful for determination of the extent of aerosol or droplet depositions as well. Certain compositions of this system can also be detected using military chemical agent detection papers such as the U.S. Military""s M8 or M9 detection papers. These papers utilize specific dye chemistries that also could be utilized to detect various levels of liquid droplet contamination.
The invention provides a relatively safe and environmentally friendly training aid for liquid G-agent (i.e., nerve agent, including VX) and H-agent (mustard-HD) simulants having varying viscosity. A preferred G agent simulant according to the invention would be a liquid mixture of dipropylene glycol monomethyl (DPGME), a fluorescent dye and a solvent such as polyethylene glycol (PEG-200) or water. The H-agent simulant is a liquid mixture of methyl salicylate (MS), a fluorescent dye and a solvent. DPGME, MS, and PEG-200 all have each been used individually and in certain combination for years as chemical agent simulants. The ion mobility characteristics of the functional groups associated with DPGME and MS lends itself well for detectability using ion mobility spectrometers (i e. the Chemical Agent Monitor (CAM)). In addition, MS and DPGME vapors can be detected by infrared, surface acoustic wave (SAW) and several other detection or monitoring technologies. DPGME and MS have been applied to random test personnel, equipment and vehicles, so the CAM could be operationally used to sort contaminated from clean personnel or materiel. Fluorescent brightening agents have been added as a fluorescence tracer to PEG-200 to see how well the simulant was applied to contaminated test vehicles. M8 or M9 detection papers can also be used to verify gross liquid or droplet contamination
The prior art to date has not produced a G or H chemical agent training simulant having the combined attributes of being a relatively innocuous material, good simulant agent liquid and vapor property correlation, a visual confirmation using a fluorescent whitening agent to show the extent of liquid contamination present, vapor signature detection by several technologies, and an actual chemical reaction simulating neutralization occurring between the training chemical agent simulant and an actual applied decontamination solution. At present, only the physical removal of decontamination procedures (i.e., soap and water, scrub brushes) can be evaluated. Therefore, present decontamination training operations using chemical agent simulants can only evaluate the mechanical process of contamination removal. Training with the present composition would simulate both the chemical neutralization and physical removal of the contamination. This system would provide a much better method for contamination assessment and decontamination effectiveness, to be used in training of military and hazardous materials responders.
The invention provides relatively safe, environmentally friendly (i.e., non-listed Resource Conservation Recovery Act (RCRA)) chemical mixtures that can be used to demonstrate a G or H agent liquid or vapor behavior and simulate the neutralization reaction which occurs when the simulant is exposed to a decontamination solution. The fluorescent tracer added to the simulants allows a visual confirmation of contamination present before and after decontamination procedures with the use of an UV lamp. The chemical agent simulants can be thickened in various degrees by adding a thickening agent such as polymethyl methacrylate polymer in order to achieve the desired liquid or liquid mixture viscosity.
The invention provides a chemical agent simulant composition which comprises:
(a) at least one vapor generating component having a vapor pressure of from about 0.1 to about 30 mm Hg at 25xc2x0 C. which is present in an amount sufficient to be detectable by vapor detection apparatus;
(b) at least one fluorescent dye in an amount sufficient to be visibly detectable when irradiated by ultraviolet light; and
(c) at least one solvent in an amount sufficient to form a substantially uniform dispersion of the vapor generating component and the fluorescent dye.
The invention also provides a method of simulating the presence of chemical agents on a surface which comprises:
i) contacting a surface with the above chemical agent simulant composition: and
ii) detecting at least one of the vapor generating component and the fluorescent dye. In some circumstances the simulant solve system may also be detected using liquid detector dye papers such as M8 or M9 detector papers.
The invention further provides a method of simulating the decontamination of a surface with a chemical agent which comprises:
i) contacting a surface with the above chemical agent simulant composition;
ii) detecting at least one of the vapor generating component and the fluorescent dye;
iii) chemically modifiying the chemical agent simulant composition; and
iv) optionally redetecting the presence or absence of at least one of the vapor generating components and/or the fluorescent dye to determine the effectiveness of the decontamination.
In the practice of the present invention, a chemical agent simulant composition is prepared which is composed of at least one vapor generating component having a vapor pressure of from about 0.1 to about 30 mm Hg at 25xc2x0 C.; at least one fluorescent dye; and at least one solvent.
The vapor generating component can be any material having a vapor pressure of from about 0.1 to about 30 mm Hg at 25xc2x0 C. Such non-exclusively include fragrances, flavorants, and such materials as methyl salicylate, diethylene glycol monomethyl ether, dipropylene glycol monomethyl ether, diethyl malonate, dimethyl sulfoxide, butyl mercaptan isoamyl acetate, dimethyl methyl phosphonate, methyl benzoate, n-dodecane thiol, butyl salicylate, cyclohexanone, dihexylether, dypnone, n-ammnopropyl morpholine, n-(2-hydroxyethyl) morpholine, di(2-ethylhexyl)ether, 2-undecanol, 2-hydroxyethyl-n-octyl sulfide, n,n-diethyl-m-toluamide, n-octyldecanethiol, phenyl ethyl phenyl acetate, clove oil, peppermint oil, and mixtures thereof. Preferably the vapor generating component comprises dipropylene glycol monomethyl ether, methyl salicylate or a mixture of dipropylene glycol monomethyl ether and methyl salicylate. The vapor generating component is preferably present in the composition in an amount of from about 5% to about 80% by weight of the composition. A more preferred range is from about 5% to about 50% and most preferably from about 5% to about 20%.
The composition then contains a fluorescent dye component. The fluorescent dye may comprise a component such as stilbenes, coumarins, triazines, thiazoles, benzoxazoles, xanthenes, triazoles, oxazoles, thiophenes, pyrazolines, derivatives of naphthalene dicarboxylic acids, derivatives of heterocyclic dicarboxylic acids, derivatives of cinnamic acid and mixtures thereof Examples of suitable fluorescent dyes nonexclusively include 2,2xe2x80x2-(thiophenediyl)-bis-(t-butyl benzoxazole); 2-(stilbyl-4xe2x80x3)-(naphtho-1xe2x80x2,2xe2x80x24,5)-1,2,3-triazole-2xe2x80x3-sulfonic acid phenyl ester; and 7-(4xe2x80x2-chloro-6xe2x80x3-diethylamino-1xe2x80x2,3xe2x80x2,5xe2x80x2-triazine4xe2x80x2-yl)amino-3-phenyl coumarin. Other useful fluorescent dyes include those described in U.S. Pat. Nos. 2,784,183; 3,644,394 and xe2x80x9cThe Production and Application of Fluorescent Brightening Agentsxe2x80x9d by Milos Zahradnik, John Wiley and Sons, New York, 1982. The fluorescent dye component is preferably present in the overall composition in an amount of from about 0.05% to about 0.5%, more preferably from about 0.05% to about 0.25% and most preferably from about 0.5% to about 0.1%. The most preferred fluorescent dyes are available commercially as Tinopol CBS-X and Tinopol FRP from Ciba Geigy.
The composition then contains a solvent capable of substantially uniformly dispersing the other composition components. xe2x80x9cSubstantially uniformly dispersedxe2x80x9d means that the vapor-generating component and the fluorescent dye component are contained in a dispersion at a relatively uniform concentration throughout the dispersion. Of course, a xe2x80x9cdispersionxe2x80x9d comprises a system consisting of a dispersed substance and the medium in which it is dispersed. In addition, the dye component and the vapor generating component do not react or otherwise interfere with one another, remaining independent entities in solution. Suitable solvents nonexclusively include water, polyethylene glycol, methyl methyacrylate, glycols, glycerol, trialkylanines, vinyl alcohol, urea, C1 to C4 alcohols, and mixtures thereof. The most preferred solvents are water and polyethylene glycol such as PEG-200 which is a polyethylene glycol having an average molecular weight of about 200. The solvent is preferably present in an amount of from about 20% to about 90% by weight of the composition, more preferably from about 20% to about 50% and most preferably from about 20% to about 25%.
The composition may further comprise one or more components useful for maintaining shelf life and precluding environmental breakdown of the components in the composition. Such may include buffering agents such as carbonate and phosphate buffers which maintain pH; thickening agents such as polymethyl methacrylate; and surfactants such as natural and synthetic soaps, particularly anionic, cationic and nonionic surfactants. These optional components, when they are used, may be present in an amount of from about 0.05% to about 5% by weight of the composition, more preferably from about 0.05% to about 3% and most preferably from about 0.05% to about 2%.
A preferred embodiment of a G agent simulant is a liquid mixture of dipropylene glycol methyl ether (DPGME), a fluorescent dye and a solvent such as polyethylene glycol or water. The preferred H-agent simulant is a liquid mixture of methyl salicylate (MS), a fluorescent dye and a solvent.
The simulant composition is used by applying it, such as by spraying or brushing onto a surface, which may include the skin and clothing of military personnel, as well as equipment. The vapors of the simulant composition can be detected by a variety of equipment such a ion mobility spectrometers, Chemical Agent Monitors (CAM devices), infrared detectors, and surface acoustic wave detectors, etc. which have been suitably calibrated for the detection of the simulant composition signatures. The vapor characteristics of the composition (i.e., vapor pressure, vapor density, volatility) are comparable to G and H agents and liquid characteristics (i.e., viscosity, liquid density) and can be adjusted accordingly by adding either more solvent or a thickener. The dye can be visibly monitored by shining an ultraviolet light onto the surface applied with the composition. The addition of the dye as a fluorescent tracer does not interfere or react with the corresponding chemical functional groups, which produce the desired detection behavior of MS and DPGME. However, when exposed to an actual decontamination solution, both the vapor generating component and fluorescent component will be chemically modified, i.e. it will degrade or neutralize these signature components, thus simulating their chemical removal via neutralization. In use, after detection of the simulant composition, its chemical modification can be simulated by contacting the chemical agent simulant composition with a mixture of water and a soap, a detergent or bleach such as sodium hypochlorite, a peroxide or other oxidizing agent, followed by a re-testing of the treated area. The chemical modification solution quenches the dye and simulant and removes the vapor and UV visibility signature of the simulant composition. As used in this invention, chemical modification includes a physical removal as well as an in situ neutralization of the chemical agent simulant composition.